Generally speaking, printing systems (e.g., printers, copiers, fax machines, etc.) include a print head or print engine for applying visual images (e.g., graphics, text, etc.) on a page, label, or other type of printable media.
A thermal printer, for example, generates pressure and heat which is delivered via a thermal print head assembly to produce an image on print media. In this regard, varying the amount of pressure and/or heat delivered by the thermal print head results in a range of darker or lighter print being applied onto the media.
Thermal printers generally require calibrating adjustments relating to the amount of pressure and/or heat that is delivered through the print head to the print media in order to achieve optimal printing output. These modifications typically require manual adjustments involving trial-and-error.
With regard to the amount of print head pressure that is delivered through the thermal print head, proper adjustment is needed in order to balance print quality (e.g., accurate black levels) with print head longevity given that high print head pressure can negatively affect the print head's life span.
A sub-aspect relating to the amount of print head pressure applied during printing relates to the pressure difference that is applied by the print head across the width of the print media (i.e., pressure bias). For example, if the print head pressure applied is greater on one side of the print medium in comparison with the other side of the print medium, the side with heavier pressure applied will have darker print in comparison to the other side which will have lighter print.
The application of unbalanced print head pressure may be particularly problematic when print media is not evenly aligned with the print head; for example, in printers where the media is aligned against the spine of the printer rather than centered on the print head (e.g., “left-adjust” printers). Notably, utilizing print media that is narrower than the total print head width tends to result in greater pressure on the side of the print media closer to the printer spine unless the print head pressure distribution across the width of the print media is properly adjusted (i.e., adjustment so equal pressure is being applied by the print head across the width of the print media).
Adjusting and calibrating the overall amount of pressure applied by a print head onto print media during printing has traditionally involved a manual process including: printing a test pattern image having a consistent side-to-side print pattern on a label or other print media (i.e., a consistent pattern across the media width); tightening or loosening an overall-pressure-adjustment screw; printing another test pattern; and repeating the procedure as needed until the applied pressure “looks right” based upon the results of the printed test pattern. In this regard, however, pressure settings that may “look right” to the operator's eye may not produce optimal images (e.g., may not actually produce a printed bar code of the desired ANSI quality) and could have negative effects for printer life span (e.g., overtightening the print head pressure adjustment resulting in premature print head failure).
Adjusting the pressure bias or pressure difference applied by the print head across the width of the print media has also traditionally involved manual adjustments. Some printers include a “left-side” and a “right-side” pressure adjustment screw, generally of the same type as described above with regard to overall print head pressure adjustment. The pressure bias adjustment or calibrating process/procedure is typically similar to the above-described process relating to adjusting overall print head pressure (e.g., the user prints a test label having a consistent side-to-side print pattern across the width of the label or other media; the user tightens or loosens one of the pressure adjustment screws; and the user repeats the process as necessary until the test pattern output “looks right” or appears the same across the media surface).
Traditional adjustment and calibration approaches, such as those described above, take a relatively long time to perform. Further, obtaining effective results is highly reliant on operator experience to determine if the print head pressure settings are optimal, and perceived results are subjective. As a result, print output may be of inferior quality and/or print head life span may be negatively affected (e.g., the print head fails at an earlier than necessary rate resulting in higher operational costs) though visual inspection appears to indicate high quality.
Therefore, a need exists for more effective printing systems and methods, including but not limited to printer systems and methods that facilitate accurate detection and adjustment of print head pressure.